Dávid Sik Kristóf Csorba Péter Ekler Implementation of a geographic information system with big data environment on common data model. 181-184 2017 CogInfoCom https://doi.org/10.1109/CogInfoCom.2017.8268238 conf/coginfocom/2017 db/conf/coginfocom/coginfocom2017.html#SikCE17